Microsoft Outlook 2010 error message: 

The server you are connected to is using a security certificate that cannot be verified. The target principal name is incorrect.

outlook error message

If you see this message, it's usually caused by a mismatch in enabling SSL and the port number as entered in your Outlook account settings. 

You'll want to make sure that your incoming and outgoing server port settings match those below:

Email Settings
UsernameYour full email address
PasswordYour password (Same for Incoming and Outgoing server)
Password Encryption / SPANot supported
IMAP Port (SSL)993
IMAP Port143
POP3 Port (SSL)995
POP3 Port110
SMTP AuthenticationRequired
SMTP Port (SSL)465
SMTP Port587
Web-Based Email